Backspacing mechanism



1955 B. F. MADSEN 2,701,045

, BACKSFACING MECHANISM Filed NOV. 8, 1951 2 Sheets-Sheet l FIG. I

3' E I I"; 28 I d 38 32 37 55 FIG. 2

. INVENTOR HERTHEL F. MADSEIN FIG. 4 g fi ATTORNEY Feb. 1, 1955 B. F. MADSEN BACKSPACING MECHANISM 2 Sheets-Sheet 2 Filed NOV. 8, 1951 FIG. 6

INVE'NTOR BERTHEI. IF. MADSEN I BYZW A TTORNEY United States Patent BACKSPACING MECHANISM Barthel F. Maclsen, Chicago, Ill.,

assignor to Teletype Corporation, Chicago,

The present invention relates to printing telegraph apparatus and more particularly to character spacing mechanism therefor.

The primary object of the invention is to provide a telegraph printer having facilities responsive to code signals whereby the movable carriage of the printer apparatus is back spaced or moved in a direction reverse to the normal character spacing movement of the carriage.

The invention features in a telegraph printer having a movable carriage, a carriage spacing mechanism comprising means for driving said carriage, said driving means including a pair of drive members cooperable with said driving means, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members effective alternatively upon said driving means in one manner to effectuate forward spacing movement to said carriage, and means for rendering said pair of drive members alternately engageable with said driving means in a difierent manner to effectuate back spacing movement to said carriage.

The foregoing and other objects of the invention will be more apparent in the following detailed description of the invention when taken in conjunction with the accompanying drawings, in which:

Fig. l is a side elevational view, partly in section, of the selective control unit substantially at the position of the back space function lever;

Fig. 2 is a fragmentary side elevational view of the back space mechanism;

Fig. 3 is a front elevational view of the back space mechanism according to the invention;

Fig. 4 is a schematic elevational view of a printer embodying the mechanism according to the present invention;

Fig. 5 is a front elevational view of a modified form of the invention in one condition of operation;

Fig. 6 is a front elevational view of said modified form of the invention in another condition of operation, and

Fig. 7 is a front elevational view of the carriage return mechanism according to the present invention.

Having reference to Fig. 1, there is shown the basic function mechanism with which the back spacing mechanism according to the present invention is associated. This basic function mechanism is located in the receiving page printers at all outlying stations. For a more thorough description of the printer with which the basic function mechanism shown in Fig. 1 is designed to be used, reference should be had to United States Patent No. 2,505,729, the disclosure of which is incorporated herein by reference.

A set of five code bars 20 is suitably mounted within the printer, which code bars are comparable to code bars 62 to 66 of said Patent No. 2,505,729. Each of said code bars 20 is movable longitudinally to one of two positions in accordance with the marking and spacing impulses of the well known Baudot code. A plurality of function bars 21 are suitably mounted in the apparatus with respect to the code bars 20, and are urged to the right towards the code bars 20 by means of springs 22 individual to each function bar 21. Each function bar 21 has a plurality of code projections 23 which cooperate with code notches 24 in each of the code bars 20.

A continuously rotating power shaft 25 carries an eccentric cam 26. A collar 27 is mounted rotatably on the eccentric 26 and has an arm 28 to which a lever 29 is secured pivotally at 31. The lever 29 is mounted pivotally on a stationary shaft 32. A bail 33 has a pair of arms 34 which are mounted pivotally on a stationary 2,701,045 Patented Feb. 1, 1955 shaft 35. A pair of toggle links 36 are secured pivotally at 37 to the arms 34, and are secured at the other ends thereof to pivots 38 to which the lever 29 is also secured. As the shaft 25 rotates, the lever 29 is oscillated about the shaft 32 to thereby, through the toggle links 36, oscillate the bail 33.

A function pawl 41 has an elongated slot 42 by means of which the function pawl 41 is mounted for longitudinal movement on a shaft 43. A spring 44 continuously urges the function pawl 41 to the right (Fig. 1) and counterclockwise about the shaft 43. The function pawl 41 has a latching shoulder 45 which cooperates with a shoulder 46 on the function bar 21. Normally the latch 45 rides on the top of the shoulder 46 (as illustrated in Fig. 1) thereby permitting the spring 44 to retain the function pawl 41 in its righthand position. A function operating lever 48 is mounted pivotally on a shaft 49 and cooperates with a laterally directed portion 51 on the function pawl 41. The function operating lever 48 is biased in a clockwise direction by a spring 52 anchored on individual anchor members 53. Associated with the lower end of the function operating lever 48 is an interponent member 54, the purpose of which will be later described. Interponents 54 are slidably carried in a guide bracket 55.

Assuming that the permutation of positions of the code bars 20 has been set up which corresponds to the function bar 21, the bail 33 moves to the right and all of the projections 23 are opposite notches 24. The spring 22 is thereby permitted to move the function bar 21 to the right, the projections 23 entering the notches 24, and the shoulder 46 underriding the latching shoulder 45 to thereby engage said latching shoulder 45 due to the action of spring 44 upon function pawl 41. Thereafter as the bail 33 moves back to the left during its return stroke it moves the function bar 21 also, the function bar 21 in turn moving the function pawl 41 to the left. As the function pawl 41 moves to the left in this manner, the lateral projection 51 thereon engages and pivots the function operating lever 48 counterclockwise against the action of spring 52, thereby causing the interponent 54 to be thrust rightwardly (as viewed in Fig. 1).

During the above-mentioned selective operation of function bar 21, the function pawl 41 was shifted from its solid line position to the dotted line position 56 over a vertically reciprocating bail member 57. Thereafter, as a new selection is being made in the code bars 20, the bail 57 moves upwardly to strip the function pawls 41 from Iljatchiilg engagement with their corresponding function ars Having reference to Figs. 2 and 3, the character spacing mechanism of the present invention is exemplified by a spacing ratchet member 61 and a pair of driving pawl members 62 and 63. The pawl members 62 and 63 are connected to eccentrics 64 and 65, respectively, which are mounted on a cross shaft 66. Power for operating the cross shaft 66 is derived from the main shaft (not shown) through a spacing clutch comparable to clutch 108 shown in Figs. 29, 31 and 32 of said United States Patent No. 2,505,729.

The spacing ratchet member 61 is integral with and rotates the drum or pulley 67, comparable to pulley 362 shown in Fig. 25 of said Patent No. 2,505,729 around which the strap or cable 444 is wound to effect character spacing movement of the type carrier 73. To effect this movement in the present embodiment of the invention. the pawl members 62 and 63 are adapted to be alternately effective in a forward driving action to impart rotative motion to the ratchet member 61.

In Fig. 4 is illustrated schematically an arrangement showing the application of the invention to a printer; of the type, for example, shown in said Patent No. 2,505,729. The strap 68 is adapted to be wound around i a carriage return drum 69, and extends around idler pulleys 71 and 72 to the spacing drum 67. Fixed to the strap 68 is a movable type carriage 73 adapted to cooperate with a fixed platen 74. With the arrangement according to the present invention forward spacing and back spacing are accomplished in a step-by-step manner, and normal carriage return is also contemplated. As is well known, the forward spacing movement (clockwise) imparted to drum 67 tends to wind up the carriage return spring in the carriage return drum 69. Then, when the pawls 62 and 63 are operated in a manner to be described to effect back spacing, the drum 67 is permitted to rotate counterclockwise due to the pull of the carriage return spring under the control of the pawls 62 and 63.

Having reference to Fig. 2, the interponent 54 is pivotally articulated to a bell crank lever 75 which is mounted pivotally on a pivot shaft 76. Normal counterclockwise rotation is imparted to lever 75 by a spring 77.

The free extremity of the horizontal arm 78 of lever 75 extends through the front plate 79 of the printer and cooperates with an arm 81 of a composite lever 82. Lever 82 is also provided with an arm 83 which cooperates with an arm 84 of a spacing pawl fulcrum member 85 mounted pivotally on a stud shaft 86 carried on a bracket 87 secured to the front plate 79 of the printer by screws 88 and 89. Member 85 normally tends to rotate in a clockwise direction (as viewed in Fig. 3) by means of a spring 91. Member 85 is also provided with a fulcrum portion 92 about which the pawl members 62 and 63 are adapted to pivot under certain operating conditions, as will hereinafter appear.

As previously mentioned, the lever 82 was referred to as a composite lever. This is for the reason that said lever 82 comprises two portions 93 and 94 which are relatively adjustable. For example, portion 94 is provided with a pair of spaced lugs, and the portion 93 is provided with a single lug adapted to be positioned between said pair of lugs. In this manner, the angular relationship between portions 93 and 94 may be readily adjusted by loosening the clamp screw 95 and inserting a screw driver or similar instrument between said lugs, on one side or the other of lug 93, depending upon whether it is desired to make the angle between arms 81 and 83 greater or less.

In the normal operation of the forward spacing mechanism, the shaft 66 rotates 180 so that the pawls 62 and 63 are effective alternatively to move the type carriage one character space; that is, from the position shown in Fig. 3 the pawl 63 is in readiness to step the spacing ratchet wheel 61 one angular step in a clockwise direction commensurate with character spacing, while the pawl 62 is retracted one step. Then upon the next one-half rotation of the shaft 66, the pawl 63 accomplishes the spacing movement, while the pawl 62 is slid back over the ratchet teeth in readiness for its next effective movement. It is observed that for forward character spacing, the pawls 62 and 63 are constantly engaging the periphery of the ratchet wheel 61 due to the pull of individual springs (not shown). That is, when the pawls 62 and 63 are drawn back to pick up the next tooth, the pawls merely ride over the ratchet teeth, and are not lifted therefrom.

As previously mentioned, during forward character spacing movement, the drum 67 is rotated clockwise to wind up the carriage return spring in the drum 69. Therefore, to effect backward spacing movement, facilities are provided to permit the ratchet wheel 61 to escape step-by-step under the pull of the carriage return spring. These facilities comprise a signal controlled means for conditioning the fulcrum 92, to render the fulcrum 92 effective to impart an escapement action to the pawls 62 and 63.

In response to a code combination of signals indicative of back spacing, the code bars 20 will be set according thereto, to permit selection of function bar 21 and consequent operation of lever 48 in a counterclockwise direction, whereupon interponent 54 is actuated rightwardly (Figs. 1 and 2) to impart clockwise movement to bell crank lever 75 (Fig. 2). Clockwise movement of lever 75 causes the arm 78 thereof to depress the arm 81 of composite lever 82 thereby imparting clockwise movement (Fig. 3) to the lever 82, to cause the arm 83 thereof to impart counterclockwise movement to the spacing pawl fulcrum member 85 against the action of spring 91.

Carried on member 85 is the afore-mentioned fulcrum portion 92, which during character spacing movement in a forward direction is spaced from said pawls 62 and 63 to permit said pawls 62 and 63 to ride constantly on the periphery of ratchet 61. Thus, upon counterclockwise movement of member 85, the fulcrum portion 92 will be moved into engagement with said pawls 62 and out of engagement with the teeth of the ratchet wheel 61 in the normal stop position shown in Fig. 3. Then, upon rotation of the eccentrics 64 and 65, the pawls 62 and 63, instead of having only reciprocatory motion imparted to them, will now have both rotary and reciprocating motion imparted to them. In addition to the afore-described reciprocating motion of said pawls the rotary motion will be imparted about the fulcrum 92. For example, from the normal stop position shown in Fig. 3, the pawl 62, during one-half revolution of eccentric 64, will be drawn back to permit ratchet 61 to follow in a counterclockwise or backward spacing direction under the pull of the carriage return spring. This is possible because substantially simultaneously therewith, the pawl 63 will be rotated about fulcrum 92 to lift the pawl tooth thereof out of engagement with the ratchet tooth. Then, upon the next one-half revolution of shaft 66 with its eccentrics 64 and 65, the pawl 63 will be drawn back to allow ratchet 61 to follow it in a counterclockwise direction. At the same time, pawl 62 will be rotated about fulcrum 92 to lift the pawl tooth thereof from engagement from the ratchet wheel 61. Thus, this action continues so long as back space signals are received, it being understood that a single back space operation occurs in response to each back space signal. With the arrangement according to the present invention, the printing of a character can proceed as described in said Patent No. 2,505,729, simultaneously just as readily during the back spacing operation as with the forward character spacing operation.

A modified form of the present invention is shown in Figs. 5 and 6. In this embodiment, the spacing ratchet 101 mounted on shaft 102, cooperates with a pair of spacing pawls 103 and 104 carried on a pair of eccentric cams 105 and 106, respectively, which in turn are fixed on a shaft 107. Cooperating with the pawls 103 and 104 is a back space fulcrum member 108 mounted pivotally on a stud 109. Member 108 is normally biased in a clockwise direction about stud 109 by a spring 111. Fulcrum member 108 is provided with a fulcrum stud 112 adapted to cooperate selectively with appropriate bearing surfaces 113 and 114 on pawls 103 and 104. Cooperating with a suitable cam surface 115 on the fulcrum member 108 is a coacting cam surface 116 on a laterally directed flange 117 of a back space control lever 118.

Lever 118 is comparable to lever shown in Fig. 2, and is normally positioned for forward character spacing as shown in Fig. 6, with the flange 117 ineffective to cam the fulcrum member 108 counterclockwise against the pull of spring 111. In this condition reciprocative motion only is imparted to the pawls 103 and 104 to effect clockwise rotation to the ratchet wheel 101. Upon receipt of a back space code signal, the lever 118 Will be actuated clockwise in the manner described in connection with the preferred embodiment of the invention. As a result of this clockwise movement of lever 118, the cam surface 116 coacts with cam surfaces 115 to impart counterclockwise movement to fulcrum member 108 to bring fulcrum 112 into contactual engagement with bearing surfaces 113 and 114 without lifting the teeth of pawls 103 and 104 from engagement with the periphery of ratchet wheel 101 when the eccentrics 105 and 106 assume the relationship shown in Fig. 6.

With the spacing mechanism conditioned for back spacing as shown in Fig. 5, the eccentrics 105 and 106 upon rotation will impart a combination of rocking motion about pivot or fulcrum 112 and vertically reciprocating motion to the rack members 103 and 104 The relative movements of pawls 103 and 104 to effect back spacing are the same as described in connection with thed preferred form of the invention shown in Figs. 2 an From the foregoing, it is observed that part of the carriage return mechanism is involved in the back spacing function; that is, the power for back spacing the type carrier step-by-step is derived from the carriage return spring under the control of the spacing pawls. Having reference to Fig. 7, the pawls 103 and 104 are operative alternatively to effect clockwise or counterclockwise rotation of ratchet wheel 101 as described in Figs. 5 and 6. Cooperating with the pawls 103 and 104 is a bell crank member 121 mounted pivotally on a stud 122. Member 121 is provided with a laterally directed portion 63 without lifting the teeth of said pawls 62 and 63 123 adapted to cooperate with the pawls 103 and 104.

Member 121 is also pivotally articulated to a depending hook member 124. A spring 125 normally tends to im part upward movement to the member 124, which through its pivotal articulation with bell crank member 121 biases member 121 normally in a clockwise direction.

The hook extremity of member 124 is adapted to engage the lower edge of an interponent member 126 which is pivotally mounted on the printer frame member. Cooperating with interponent 126 is the horizontal arm of a lever 127 mounted pivotally at 128. Lever 127 is comparable to lever 75 shown in Fig. 2. A latch member 129 cooperates with the interponent 126. and is adapted to hold said interponent 126 depressed during the carriage return operation. Latch member 129 is provided with a latch arm 131 and an unlatch arm 132. and is normall biased counterclockwise about pivot 133 by a sprin 134. Integral with the ratchet wheel 101 is an arm 135 having a pin 136 extending laterally therefrom at the free end of said arm. Thus, through the pin 136. the arm 135 cooperates with the arm 132 of latch lever 129.

In the operation of the arrangement shown in Fig. 7, the ratchet wheel 101 is rotated clockwise for forward character spacing by the pawls 103 and 104 as previously described, with the pin 136 moving away from the arm 132. Then, when a carriage return signal is received the lever 127 is caused to be actuated clockwise to depress interponent 126. which throu h hook member 124 will rotate be l crank 121 counterclockwise to cause la er"l p rtion 123 thereof to disenga e the pawls 103 and from the ratchet wheel 101. Simu taneously. the intern nent 126 will become latched up bv the l tch p r i n 131 of latch lever 129. The ratchet wheel 101 a d arm 135 are now free to be rotated counterclockwise b the carriage return spring in well known manner. hi counterclockwise rotation will continue until the pin 136 strikes the unlatching arm 132 of latch lever 129. whereupon the lever 129 is rotated clockwise to disengage latch 131 from interponent 126. Through the pull of spring 125 on member 124, the bell crank 121 will be returned to its clockwise position to permit re-engagement of awls 103 and 104 with the ratchet 101.

It is to be understood that the above-described arrangement is merelv illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement to said carriage, and means for rendering said pair of drive members alternately engageable with said instrumentality in a different manner to effectuate backward spacing movement to said carriage.

2. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement to said carriage, fulcrum means for rendering said pair of drive members alternately engageable with said instrumentality in a different manner to effectuate backward spacing movement to said carriage, and means for conditioning said fulcrum means to selectively effectuate said movements.

3. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement to said carriage, means for rendering said pair of drive members alternately engageable with said instrumentality in a 85 6 78 different manner to effectuate backward spacing movement to said carriage, and means for rendering said drive members ineffective to effectuate said movements.

4. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement to said carriage, means for rendering said pair of drive members alternately engageable with said instrumentality in a different manner to effectuate backward spacing movement to said carriage, means for rendering said drive members ineffective to effectuate said movements. and means controlled by said instrumentality for restorin the effectiveness of said drive members.

5. In a telegraph printer having a movable carriage. carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement of said carriage, fulcrum means for said drive members, and means for conditioning said fulcrum means for rendering said pair of drive members alternately engageable with said instrumentality in a different manner to effectuate backward spacing movement to said carriage.

6. in a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality. a pair of eccentric means individually associated with said drive members to actuate said drive members. said drive members alternatively effective upon said instrumentality in one manner to effectuate forward spacing movement to said carriage, fulcrum means for said drive members, means for conditioning said fulcrum means for rendering said pair of drive members alternately engageable with said instrumentality in a different manner to effectuate backward spacing movement to said carriage, and further means for rendering said drive members ineffective to effectuate said movements.

7. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising an instrumentality for driving said carriage, a pair of drive members cooperable with said instrumentality, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members actuated alternatively under certain conditions of operation in a reciprocatory manner to impart through said instrumentality a forward spacing movement to said carriage, and means effective under other conditions of operation to impart combined reciprocatory and rotary motion to said drive members to render said pair of drive members alternately engageable with said instrumentality to effectuate backward spacing movement to said carriage.

8. In a telegraph printer having a movable carriage,

carriage spacing mechanism comprising a pair of drive members, a pair of eccentric means individually asso ciated with said drive members to actuate said drive mem bers, said drive members alternatively effective in one manner to effectuate forward spacing movement to said carriage, and means for rendering said pair of drive members alternatively effective in a different manner to effectuate backward spacing movement to said carriage.

9. In a telegraph printer having a movable carriage, carriage spacing mechanism comprising a pair of drive members, a pair of eccentric means individually associated with said drive members to actuate said drive members, said drive members alternatively effective in one manner to effectuate forward spacing movement to said carriage, control means for rendering said pair of drive members alternatively effective in a different manner to effectuate backward spacing movement to said carriage, and means for conditioning said control means to selectively effectuate said movements.

References Cited in the file of this patent UNITED STATES PATENTS Crawley Oct. 9, 1923 

